package github.lyf.simple;

/**
 * @author yunfei.li
 * @date 2021/10/8 17:15
 */
public class LongestCommonPrefix {
    /**
     * 编写一个函数来查找字符串数组中的最长公共前缀。
     * <p>
     * 如果不存在公共前缀，返回空字符串 ""。
     * <p>
     *  
     * <p>
     * 示例 1：
     * <p>
     * 输入：strs = ["flower","flow","flight"]
     * 输出："fl"
     * 示例 2：
     * <p>
     * 输入：strs = ["dog","racecar","car"]
     * 输出：""
     * 解释：输入不存在公共前缀。
     *  
     * <p>
     * 提示：
     * <p>
     * 1 <= strs.length <= 200
     * 0 <= strs[i].length <= 200
     * strs[i] 仅由小写英文字母组成
     *
     * @param strs
     * @return
     */
    public static String longestCommonPrefix(String[] strs) {
        String minLengthStr = strs[0];
        for (int i = 1; i < strs.length; i++) {
            if (strs[i].length() < minLengthStr.length()) {
                minLengthStr = strs[i];
            }
        }
        if (minLengthStr.length() == 0) {
            return "";
        }
        int start = 0;
        int end = 0;
        for (; end < minLengthStr.length(); end++) {
            if (!containsStr(minLengthStr.substring(start, end + 1), strs)) {
              break;
            }
        }
        return minLengthStr.substring(start, end);
    }

    private static boolean containsStr(String str, String[] strs) {
        for (String s : strs) {
            if (!s.startsWith(str)) {
                return false;
            }
        }
        return true;
    }

    /**
     * 题解2
     * @param strs
     * @return
     */
    public String longestCommonPrefix1(String[] strs) {
        if (strs == null || strs.length == 0) {
            return "";
        }
        String prefix = strs[0];
        int count = strs.length;
        for (int i = 1; i < count; i++) {
            prefix = longestCommonPrefix(prefix, strs[i]);
            if (prefix.length() == 0) {
                break;
            }
        }
        return prefix;
    }

    public String longestCommonPrefix(String str1, String str2) {
        int length = Math.min(str1.length(), str2.length());
        int index = 0;
        while (index < length && str1.charAt(index) == str2.charAt(index)) {
            index++;
        }
        return str1.substring(0, index);
    }
}
